Single-layer circuit board, multi-layer circuit board, and manufacturing methods therefor

ABSTRACT

A single-layer circuit board, multi-layer circuit board, and manufacturing methods therefor. The method for manufacturing the single-layer circuit board ( 10 ) comprises the following steps: drilling a hole on a substrate ( 11 ), the hole comprising a blind hole and/or a through hole (S 1 ); on a surface ( 12 ) of the substrate, forming a photoresist layer having a circuit negative image (S 2 ); forming a conductive seed layer on the surface ( 12 ) of the substrate and a hole wall ( 19 ) of the hole (S 3 ); removing the photoresist layer, and forming a circuit pattern on the surface ( 12 ) of the substrate (S 4 ), wherein Step S 3  comprises implanting a conductive material below the surface ( 12 ) of the substrate and below the hole wall ( 19 ) of the hole via ion implantation, and forming an ion implantation layer as at least part of the conductive seed layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/773,772, filed May 4, 2018 which is a U.S. national stageapplication under 35 U.S.C. § 371 of PCT/CN2016/000649, filed on Nov.23, 2016, which claims the benefit of and priority to Chinese PatentApplication No. 201510747884.1, filed Nov. 6, 2015, the contents ofwhich are herein incorporated by reference in their entirety.

DESCRIPTION Field

the invention relates to single-layer circuit board, multi-layer circuitboard and manufacturing methods thereof. Especially, the inventionrelates to single-layer circuit board with insulated material having ahole as substrate and formed with conductor layer on the hole wall andformed with circuit pattern on the substrate surface, multi-layercircuit board laminated by plenty of single-layer circuit boards andwherein each single-layer circuit board is connected via metalized viahole, and manufacturing methods thereof.

Background

In the circuit board industry, metalized via hole is widely used toconnect surface of circuit board and circuit pattern on back side orelectronic means or the like, or electrically connects conductor layerbetween each layer circuit board of double-layer or multi-layer circuitboard to each other, so as to implement the design of multi-layercircuit pattern.

In the prior art, methods of manufacturing single-layer circuit boardwith metalized via hole mainly comprises the following steps:manufacturing copper foil via flattening or electroanalysis; bonding thecopper foil on the substrate via high temperature lamination, to formoverlaying copper plate; drilling a hole and removing dirt on theoverlaying copper plate; forming conductive seed layer on the hole wallvia processes of electroless copper (PTH) or black hole, shadow or thelike; forming a metal conductor layer on the hole wall viaelectroplating, to form overlaying copper plate with metalized hole;covering the overlaying copper plate with photoresist film, usinglithography machine for exposure and development, then implementingetching to remove copper layer outside of circuit region on theoverlaying copper plate, thereby achieving circuit board with circuitpattern.

Additionally, manufacturing methods for multi-layer circuit board withmetalized via hole mainly involves stitching, comprising the followingsteps: manufacturing single-layer circuit board; implementing laying-upplate and lamination in the order of copper foil, PP (prepreg),single-layer circuit board, PP, single-layer circuit board, . . . , PP,copper foil; drilling through hole for the multi-layer plate afterlamination and drilling blind hole for upper layer copper foil, andimplementing hole metalization; applying pattern electroplating or panelelectroplating to uppermost layer and lowermost layer of the copperfoil, achieving circuit pattern. Wherein hole metalization is alsousually achieved via process of electroless copper or black hole, shadowor the like to form conductive seed layer on the hole wall and then viaelectroplating or the like to form conductor thickening layer.

In the process of forming single-layer or multi-layer circuit board withmetalized hole via above-mentioned methods, if it is desired to drill ahole with diameter of less than 100 μm on the substrate, currently laserdrilling technology has to be utilized. At the time, it need toimplement thinning in advance to the part of copper foil to be drilled,afterward use laser to drill a hole, then after drilling the hole,implement electroless copper and electroplating. However, in the etchingthinning process, once etching position generates deviation, it willresult in that drilling position on the substrate also generatesdeviation. Also, when implementing metalization to mini-hole, bindingforce between electroplating copper layer and hole wall is weak, copperlayer easily peels off from the hole wall. Additionally, the minimaldiameter of micro-hole manufactured on the overlaying copper plateutilizing prior art is 20-50 μm, when the diameter is less than 20 μm,it will generate a hole with too high thickness-diameter ratio andproblems of hole wall copper layer being nonuniform or the like willoccur at the time of electroless copper and electroplating. Withinmicro-hole region, nonuniform distribution of current density willresult in that the deposition rate of copper at micro-hole surface islarger than the deposition rate of hole wall and bottom. Therefore, voidor crack easily forms in the deposition process, it will also result inthat the copper thickness of hole surface is larger than the copperthickness of hole wall.

Additionally, above-mentioned methods of producing circuit board need toproduce finished overlaying copper plate in advance, afterwardimplementing drilling and hole metalization to the finished overlayingcopper plate, then make circuit pattern via procedure of pasting film,exposure and development, etching or the like, thus the processprocedure is long, the producing cost is high. Also, because there areseveral metal etching in the whole process procedure, thus it willgenerate plenty of waste water containing metal ion, generatingsignificant harm to environment.

BRIEF DESCRIPTION

The invention is made in view of above-mentioned problems, the aim isto, provide single-layer circuit board with metalized hole, multi-layercircuit board and manufacturing methods thereof, to simplify themanufacturing procedure of circuit board, and improve conductiveperformance of metalized hole therein.

The first technology solution of the invention is methods formanufacturing single-layer circuit board, comprising the followingsteps: drilling a hole on a substrate, the hole comprises blind holeand/or through hole (S1); forming a photoresist layer having circuitnegative image on the surface of the substrate (S2); forming aconductive seed layer on the surface of substrate and a hole wall of thehole (S3); and removing photoresist layer, to form circuit pattern onthe surface of the substrate (S4), wherein step S3 comprises implantinga conductive material below the surface of the substrate and below thehole wall of the hole via ion implantation, to form ion implantationlayer as at least part of the conductive seed layer.

According to such methods, metalized hole can be formed on a substrateand circuit pattern can be formed on the surface of such substrate viasimple process procedure. When forming circuit pattern, because beforeforming conductive seed layer, photoresist film is overlaid in advanceon the substrate surface and further forming a photoresist layer withcircuit negative image, afterward using stripping liquid to dissolvesuch photoresist layer to make the conductive seed layer and/orconductor thickening layer in non-circuit region fall off together withphotoresist layer, so there is no need to obtain circuit pattern viaetching as prior art, or at least the using of etching liquid candecrease, thereby decreasing or eliminating the harm to the environmentby etching waste water containing metal ion.

The second technology solution of the invention is that, in the firstsolution, step S3 further comprises depositing conductive material aboveion implantation layer via plasma deposition, to form plasma depositionlayer, the plasma deposition layer and the ion implantation layerconstitute conductive seed layer.

The third technology solution of the invention is that, in the firstsolution, after step S3, before step S4, methods further comprises:forming conductor thickening layer on the conductive seed layer.

The forth technology solution of the invention is that, in the firstsolution, removing the photoresist layer comprising using strippingliquid to dissolve the photoresist layer.

The fifth technology solution of the invention is methods formanufacturing single-layer circuit board, comprising the followingsteps: drilling a hole on a substrate, the hole comprises blind holeand/or through hole (S1); forming a conductive seed layer on the surfaceof the substrate and a hole wall of the hole (S2); and forming circuitpattern on the surface of the substrate (S3), wherein step S2 comprisesimplanting a conductive material below the surface of the substrate andbelow the hole wall of the hole via ion implantation, to form ionimplantation layer as at least part of the conductive seed layer.

The sixth technology solution of the invention is that, in the fifthsolution, step S2 further comprises depositing a conductive materialabove the ion implantation layer via plasma deposition, to form a plasmadeposition layer, the plasma deposition layer and the ion implantationlayer constitute the conductive seed layer.

The seventh technology solution of the invention is that, in the fifthsolution, step S3 comprises: first forming a conductor thickening layeron the conductive seed layer, then implementing pattern electroplatingor panel electroplating on the conductor thickening layer located abovethe surface of the substrate, thereby obtaining circuit pattern.

The eighth technology solution of the invention is that, in the fifthsolution, step S3 comprises: directly implementing patternelectroplating or panel electroplating on the conductive seed layerformed to the surface of the substrate, thereby obtaining circuitpattern.

The ninth technology solution of the invention is that, in any of thefirst to the eighth solutions, the substrate is rigid sheet or flexiblesheet, rigid sheet comprises one or more of organic polymer rigid plate,ceramic plate, glass plate, wherein organic polymer rigid platecomprises one or more of LCP, PTFE, CTFE, FEP, PPE, synthetic rubberplate, glass fabric/ceramic filler reinforcing plate, flexible sheet isorganic polymer thin film, which comprises one or more of PI, PTO, PC,PSU, PES, PPS, PS, PE, PP, PEI, PTFE, PEEK, PA, PET, PEN, LCP or PPA.

The tenth technology solution of the invention is that, in the first orthe fifth solutions, during ion implantation, the ions of conductivematerial gain energy of 1-1000 keV, are implanted below the surface ofthe substrate and below a hole wall of the hole for a depth of 1-500 nm,and form steady doping structure with the substrate.

The eleventh technology solution of the invention is that, in the secondor sixth solution, during plasma deposition, the ions of conductivematerial gain energy of 1-1000 eV, form a plasma deposition layer in thethickness of 1-10000 nm.

The twelfth technology solution of the invention is that, in any of thefirst to the eighth solutions, the conductive material composing theconductive seed layer comprises one or more of Ti, Cr, Ni, Cu, Ag, Au,V, Zr, Mo, Nb and alloy thereof.

The thirteenth technology solution of the invention is that, in thethird or the seventh solution, via one or more of electroplating,chemical plating, vacuum evaporation, sputtering, utilizing one or moreof Al, Mn, Fe, Ti, Cr, Co, Ni, Cu, Ag, Au, V, Zr, Mo, Nb and alloythereof, to form the conductor thickening layer with a thickness of0.01-1000 μm.

According to methods for manufacturing single-layer circuit board of theinvention, metalization of the substrate surface and metalization of thehole can be conducted simultaneously. Therefore, single-layer circuitboard with metalized via hole can be directly achieved on the substratevia one time forming, without needing as prior art that, it need tooverlay thick metal foil to the substrate in advance and afterwardimplement etching thinning to metal foil to drill a hole on thesubstrate, and it need to further form conductive layer on the hole wallvia process of chemical electroless copper or black hole, shadow or thelike, to obtain metalized via hole. Compared to prior art, the processprocedure of present methods is significantly shorter, and can decreasethe using of etching liquid, facilitating protection of the environment.Additionally, via adjusting various process parameter, these methodsvery easily achieve very thin circuit pattern layer in thickness, theresultant single-layer circuit board can advantageously be applied tomedium and high grade precision electronic product on the basis of HDI(high density interconnected base plate) and COF (flexible chip)technology. Additionally, during ion implantation, the ions ofconductive material are forcibly implanting inside of the substrate invery high speed, form steady doping structure with the substrate, whichcorresponds to forming a large number of piles below the substratesurface and the hole wall. Because the existing of piles, andsubsequently achieved conductive layer (the plasma deposition layer orthe conductor thickening layer) is connected with the piles, therefore,the binding force between finally achieved conductive layer of the baseplate and the substrate is high, much higher than the binding forcebetween magnetron sputtering achieved metal layer in prior art and theconductor. Also, the dimension of the conductive material ion for ionimplantation is usually in nanometer level, distributed relativelyuniform during ion implantation, and there is no big difference forincident angle to the substrate surface and the hole wall. Therefore, itcan ensure the subsequently formed conductor thickening layer or plasmadeposition layer above the ion implantation layer have good uniformityand compactness, without easily occurring pin hole phenomenon. Whenmicro-hole metalization, it is easy to form surface uniform compactconductive seed layer on the hole wall, and the ratio of the conductorlayer thickness of the hole wall and the conductor layer thickness ofthe substrate surface can reach 1:1, therefore when electroplating orthe like, problems of hole wall conductor layer being nonuniform andvoid or crack or the like don't occur, which can effectively improve theconductivity of the metalized hole.

The fourteenth technology solution of the invention is a single-layercircuit board, which comprises substrate and a circuit pattern layerformed to partial surface of the substrate, the substrate is providedwith a hole, the hole comprises blind hole and/or through hole, the holewall of the hole is formed with conductive seed layer, the circuitpattern layer comprises a conductive seed layer substrate formed onpartial surface, wherein the conductive seed layer comprises a ionimplantation layer implanted below partial surface of the substrate andbelow the hole wall of the hole.

Because of the existing of ion implantation layer in the hole wall, suchsingle-layer circuit board can have very high binding force between thehole wall and the conductive seed layer, thus the conductive layer ofthe hole wall wouldn't easily fall off or scuff in the subsequentvarious fabrication or application process. Therefore, it facilitatesimproving the conductivity of the hole, facilitating to achievesingle-layer circuit board with good connectivity.

The fifteenth technology solution of the invention is that, in thefourteenth solution, the ion implantation layer is located below partialsurface of the substrate and below the hole wall of the hole for a depthof 1-500 nm, and form steady doping structure with the substrate.

The sixteenth technology solution of the invention is that, in thefourteenth solution, the conductive seed layer further comprises plasmadeposition layer adhered above the ion implantation layer; the plasmadeposition layer has a thickness of 1-10000 nm.

The seventeenth technology solution of the invention is that, in thefourteenth solution, conductive seed layer is composed by conductivematerial, such conductive material comprises one or more of Ti, Cr, Ni,Cu, Ag, Au, V, Zr, Mo, Nb and alloy thereof.

The eighteenth technology solution of the invention is that, in thefourteenth solution, circuit pattern layer further comprises a conductorthickening layer located above the conductive seed layer, the conductorthickening layer has a thickness of 0.01-1000 μm, and is constituted byone or more of Al, Mn, Fe, Ti, Cr, Co, Ni, Cu, Ag, Au, V, Zr, Mo, Nb andalloy thereof.

The nineteenth technology solution of the invention is methods formanufacturing multi-layer circuit board, comprising: implementinglaying-up plate and lamination in the order of metal foil, middlesticking layer, single-layer circuit board, middle sticking layer,single-layer circuit board, . . . , middle sticking layer, metal foil(S1); drilling a hole on the multi-layer plate after lamination, thehole comprises through hole and/or blind hole (S2); forming conductiveseed layer on the hole wall of the hole (S3); and removing part of themetal foil, to form circuit pattern (S4), wherein step S3 comprisesimplanting a conductive material below the hole wall of the hole via ionimplantation, to form ion implantation layer as at least part of theconductive seed layer.

During ion implantation, the ions of conductive material are forciblyimplanted below the hole wall in very high speed, and form steady dopingstructure with the substrate, which corresponds to forming a largenumber of piles below the hole wall. Because the existing of piles, andsubsequently achieved conductive layer (plasma deposition layer orconductor thickening layer) is connected with the piles, therefore, thebinding force between the finally achieved conductive layer of the baseplate and the substrate is high, much higher than the binding forcebetween the achieved metal layer by magnetron sputtering in prior artand the conductor. Also, the dimension of the conductive material ionfor ion implantation is usually in nanometer level, distributedrelatively uniform during ion implantation, and there is no bigdifference for incident angle on the hole wall. Therefore, it can ensurethe subsequently formed conductor thickening layer or plasma depositionlayer above the ion implantation layer have good uniformity andcompactness, without easily occurring pin hole phenomenon. Whenmicro-hole metalization, it is easy to form surface uniform compactconductive seed layer on the hole wall, which can effectively improvethe conductivity of the metalized hole.

The twentieth technology solution of the invention is methods formanufacturing multi-layer circuit board, comprising: implementinglaying-up plate and lamination in the order of surface sticking layer,single-layer circuit board, middle sticking layer, single-layer circuitboard, middle sticking layer, single-layer circuit board, . . . ,surface sticking layer (S1); drilling a hole on the multi-layer plateafter lamination, the hole comprises through hole and/or blind hole(S2); forming a conductive seed layer on the outer surface of thesurface sticking layer and the hole wall of the hole (S3); and formingcircuit pattern on the outer surface of the surface sticking layer (S4),wherein step S3 comprises, implanting a conductive material below theouter surface of the surface sticking layer and below the hole wall ofthe hole via ion implantation, to form ion implantation layer as atleast part of the conductive seed layer.

According to such methods, the metalization of the outer surface of thesurface sticking layer and metalization of the hole can besimultaneously implemented. Therefore, multi-layer circuit board withmetalized via hole and surface circuit pattern can be directly achievedvia one time forming, without needing as prior art that, it need tooverlay thick metal foil in advance and afterward implement etchingthinning to metal foil to drill a hole, and it need to further formconductive layer on the hole wall via process of chemical electrolesscopper or black hole, shadow or the like, to obtain metalized via hole.Compared to prior art, the process procedure of present methods issignificantly shorter, and can decrease the using of etching liquid,facilitating protection of the environment. Additionally, via adjustingvarious process parameter, these methods very easily achieve very thincircuit pattern layer in thickness, the resultant single-layer circuitboard can advantageously be applied to medium and high grade precisionelectronic product on the basis of HDI (high density interconnected baseplate) and COF (flexible chip) technology.

The twenty-first technology solution of the invention is that, in thenineteenth or the twentieth solution, during ion implantation, the ionsof conductive material gain energy of 1-1000 keV, are implanted belowthe hole wall of the hole and/or below the outer surface of the surfacesticking layer for a depth of 1-500 nm, and form steady doping structurewith the substrate.

The twenty-second technology solution of the invention is that, in thenineteenth or the twentieth solution, step S3 further comprises,depositing a conductive material above the ion implantation layer viaplasma deposition, to form plasma deposition layer, the plasmadeposition layer and the ion implantation layer constitute theconductive seed layer.

The twenty-third technology solution of the invention is that, in thetwenty-second solution, during plasma deposition, the ions of conductivematerial gain energy of 1-1000 eV, form the plasma deposition layer in athickness of 1-10000 nm.

The twenty-fourth technology solution of the invention is that, in thenineteenth or the twentieth solution, the conductive material composingthe conductive seed layer comprises one or more of Ti, Cr, Ni, Cu, Ag,Au, V, Zr, Mo, Nb and alloy thereof.

The twenty-fifth technology solution of the invention is that, in thenineteenth solution, step S3 further comprises: forming a conductorthickening layer on the conductive seed layer formed on the hole wall.

The twenty-sixth technology solution of the invention is that, in thenineteenth or the twentieth solution, step S4 comprises: first form aconductor thickening layer on the conductive seed layer, thenimplementing pattern electroplating or panel electroplating on theconductor thickening layer located above the outer surface of thesurface sticking layer, thereby obtaining circuit pattern.

The twenty-seventh technology solution of the invention is that, in thetwenty-fifth or the twenty-sixth solution, via one or more ofelectroplating, chemical plating, vacuum evaporation, sputtering,utilizing one or more of Al, Mn, Fe, Ti, Cr, Co, Ni, Cu, Ag, Au, V, Zr,Mo, Nb and alloy thereof, to form the conductor thickening layer with athickness of 0.01-1000 μm.

The twenty-eighth technology solution of the invention is that, in thetwentieth solution, step S4 comprises: implementing patternelectroplating or panel electroplating directly on the conductive seedlayer formed on the outer surface of the surface sticking layer, therebyobtaining circuit pattern.

The twenty-ninth technology solution of the invention is that, in thenineteenth or the twentieth solution, at least one of the middlesticking layer is provided with a hole, the hole wall of such hole isformed with conductive layer.

The thirtieth technology solution of the invention is that, in thenineteenth or the twentieth solution, at least one of the single-layercircuit board is provided with hole, the hole wall of such hole isformed with conductive layer.

The thirty-first technology solution of the invention is that, in thenineteenth or the twentieth solution, the middle sticking layer and/orthe surface sticking layer comprises one or more of PP, PI, PTO, PC,PSU, PES, PPS, PS, PE, PEI, PTFE, PEEK, PA, PET, PEN, LCP, PPA.

The thirty-second technology solution of the invention is multi-layercircuit board, which is successively constituted by metal foil, middlesticking layer, single-layer circuit board, middle sticking layer,single-layer circuit board, . . . , middle sticking layer, metal foil,the multi-layer circuit board is provided with a hole, the hole wall ofthe hole is formed with a conductive seed layer, and partial region ofthe metal foil is removed to form circuit pattern layer, wherein theconductive seed layer comprises the ion implantation layer implantedbelow the hole wall of the hole.

The thirty-third technology solution of the invention is multi-layercircuit board, which is successively constituted by surface stickinglayer, single-layer circuit board, middle sticking layer, single-layercircuit board, . . . , surface sticking layer, multi-layer circuit boardis provided with hole, the hole wall of the hole is formed with aconductive seed layer, and partial outer surface of the surface stickinglayer is formed with a circuit pattern layer of conductive seed layer,wherein the conductive seed layer comprises the ion implantation layerimplanted below the hole wall of the hole and below partial outersurface of the surface sticking layer.

Because of the existing of ion implantation layer in the hole wall, suchmulti-layer circuit board can have very high binding force between thehole wall and the conductive seed layer, thus the conductive layer ofthe hole wall wouldn't easily fall off or scuff in the subsequentvarious fabrication or application process. Therefore, it facilitatesimproving the conductivity of the hole, facilitating achievingmulti-layer circuit board with good connectivity.

The thirty-fourth technology solution of the invention is that, in thethirty-second or the thirty-third solution, the ion implantation layeris located below the hole wall of the hole and/or below partial outersurface of the surface sticking layer for a depth of 1-500 nm, and formsteady doping structure with the substrate.

The thirty-fourth technology solution of the invention is that, in thethirty-second or the thirty-third solution, conductive seed layerfurther comprises a plasma deposition layer adhered above the ionimplantation layer, such plasma deposition layer has a thickness of1-10000 nm.

The thirty-fourth technology solution of the invention is that, in thethirty-second or the thirty-third solution, the conductive seed layer iscomposed by a conductive material, such conductive material comprisesone or more of Ti, Cr, Ni, Cu, Ag, Au, V, Zr, Mo, Nb and alloy thereof.

The thirty-fourth technology solution of the invention is that, in thethirty-second or the thirty-third solution, a conductor thickening layerwith a thickness of 0.01-1000 μm is formed above the conductive seedlayer.

The thirty-fourth technology solution of the invention is that, in thethirty-second or the thirty-third solution, the hole is a through holethroughout the multi-layer circuit board, a blind hole formed on themulti-layer surface of the circuit board, or a blind hole formed in thesingle-layer circuit board or the middle sticking layer.

The thirty-fourth technology solution of the invention is that, in thethirty-second or the thirty-third solution, the middle sticking layerand/or the surface sticking layer comprises one or more of PP, PI, PTO,PC, PSU, PES, PPS, PS, PE, PEI, PTFE, PEEK, PA, PET, PEN, LCP, PPA.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood by one skilled in the art whenthe following detailed description is read with reference to theaccompanying drawings. For clarity, the drawings is not necessarily tothe scale, rather some portion therein might be exaggerated toillustrate details. The same characters represent the same or like partsthroughout the drawings, wherein:

FIG. 1 represents flowchart of methods for manufacturing single-layercircuit board according to the first embodiment of the invention;

FIG. 2 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 1;

FIG. 3 represents flowchart of methods for manufacturing single-layercircuit board according to the second embodiment of the invention;

FIG. 4 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 3;

FIG. 5 represents flowchart of methods for manufacturing single-layercircuit board according to the third embodiment of the invention;

FIG. 6 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 5;

FIG. 7 represents flowchart of methods for manufacturing multi-layercircuit board according to the fourth embodiment of the invention;

FIG. 8 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 7;

FIG. 9 represents flowchart of methods for manufacturing multi-layercircuit board according to the fifth embodiment of the invention;

FIGS. 10A and 10B represent sectional schematic views of respectiveproduct of each step of the methods shown in FIG. 9;

FIG. 11 represents flowchart of methods for manufacturing multi-layercircuit board according to the sixth embodiment of the invention;

FIGS. 12A and 12B represent sectional schematic views of respectiveproduct of each step of the methods shown in FIG. 11.

REFERENCE NUMBER

-   -   10 single-layer circuit board    -   11 substrate    -   12 surface of the substrate    -   13 conductive seed layer    -   131 ion implantation layer    -   132 plasma deposition layer    -   15 conductor thickening layer    -   16 circuit pattern layer    -   161 circuit region    -   162 no-circuit region    -   17 through hole    -   18 blind hole    -   19 hole wall    -   20 multi-layer circuit board    -   21 metal foil    -   22 middle sticking layer    -   23 surface sticking layer    -   24 photoresist film.

DETAILED DESCRIPTION

In the following, with reference to the drawings, the implementation ofthe invention is described in detail. It should be understood by oneskilled in the art; this description only exemplifies exampleembodiments of the invention, but by no means limits the scope of theinvention.

FIG. 1 represents flowchart of methods for manufacturing single-layercircuit board according to the first embodiment of the invention, whileFIG. 2 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 1. As shown in FIG. 1, such methodscomprises the following steps: drilling a hole on a substrate, the holecomprises blind hole and/or through hole (S1); forming a photoresistlayer having circuit negative image on the surface of the substrate(S2); forming a conductive seed layer on the surface of substrate and ahole wall of the hole (S3); and removing photoresist layer, to formcircuit pattern on the surface of the substrate (S4). FIGS. 2 (a), (b),(c) and (d) correspond to step S1, S2, S3 and S4 respectively. Referenceis made to FIG. 1 and FIG. 2 simultaneously in the following, each stepof such methods is illustrated in detail.

In the manufacturing process of circuit board, usually using insulatedmaterial as substrate, overlaying composite metal material onsingle-face or double-face of such substrate and implementing etchingthereof, thereby achieving circuit board. As an example of insulatedsubstrate, it can use rigid substrate (also known as hard plate), forexample one or more of organic polymer rigid plate, ceramic plate (suchas silicon dioxide plate), glass plate or the like, the organic polymerrigid plate can further comprises one or more of LCP, PTFE, CTFE, FEP,PPE, synthetic rubber plate, glass fabric/ceramic filler reinforcingplate, wherein glass fabric/ceramic filler reinforcing plate is sheetwith organic polymer material such as epoxy resin, modified epoxy resin,PTFE, PPO, CE, BT or the like as base material, with glassfabric/ceramic filler as reinforcing phase. Additionally, insulatedsubstrate can also use flexible plate (also known as soft plate), forexample organic polymer thin film, which comprises one or more of PI,PTO, PC, PSU, PES, PPS, PS, PE, PP, PEI, PTFE, PEEK, PA, PET, PEN, LCPor PPA.

First, there is need to drill a hole on a substrate (step S1). Althoughonly through hole 17 is shown in FIG. 2(a), but it can also drilling ablind hole on the surface 12 of the substrate 11. Through hole is thehole penetrating surface and blackface of the substrate, while blindhole is the hole penetrating inside the substrate but not penetratingsuch substrate. The shape of hole can be various shape of circle,rectangle, triangle, diamond, stepwise or the like. Drilling the holecan be conducted utilizing mechanical drilling, punching, laserdrilling, plasma etching and reactive ion etching or the like, whereinlaser drilling can further comprises infrared laser drilling, YAG laserdrilling and ultraviolet laser drilling, a micro-hole with diameter of2-5 μm can be formed on the substrate. To decrease heat impacted region,preventing edge of the hole from heat damage, preferably ultravioletlaser drilling is utilized. In the case of manufacturing flexiblecircuit board in a roll-to-roll manner, continuously drilling manner canbe utilized to form a series of holes on a roll of flexible platesubstrate. After forming a hole on the substrate, it need to clean void,to clear away impurities of drilling bits or the like existing therein.

Subsequently, forming a photoresist layer having circuit negative imageon the surface of the substrate (step S2). In particular, as shown inFIG. 2(b), painting or sticking a layer of photoresist film 24 on thesurface 12 of the substrate 11 after drilling a hole and cleaning,placing the substrate overlaid with photoresist film 24 on a lithographymachine to implement exposure and development, after washing thesubstrate surface and baking, obtaining a photoresist layer havingcircuit negative image (i.e. forming complementing image of the circuitpattern to be finally formed on the substrate surface). At the time,photoresist film 24 only exists in the no-circuit region 162 on thesubstrate surface, while such photoresist film 24 doesn't exist in thecomplementary circuit region 161 thereof.

Then, forming a conductive seed layer on the surface of substrate and ahole wall of the hole (step S3). Because photoresist film 24 is formedin the no-circuit region 162 of the substrate surface 12, thus in suchprocess, conductive seed layer 13 will also form on the surface of thephotoresist film 24. It is important that, step S3 comprises implantinga conductive material below the surface 12 of the substrate 11 and thebelow the hole wall of the hole 19 via ion implantation, to form ionimplantation layer 131, as at least part of the conductive seed layer13. It should be noted, “implanting below the hole wall” described inthe text actually refers to implanting below the substrate surface atthe hole wall (i.e., wall surface of the hole). For example, in FIG.2(c), ion implantation layer 131 is implanted below the hole wall 19 ofthe hole 17, actually refers to ion implantation layer 131 is locatedbelow the substrate surface at the hole wall 19 of the hole 17 (i.e.,wall surface of the hole).

The forming of ion implantation layer can be achieved via the followingmethods: using conductive material as target material, in ionimplantation equipment in vacuum environment, ionizing the conductivematerial in the target material via arcing to generate ion, thenaccelerating such ion in the electric field with high voltage to gainvery high energy, for example 1-1000 keV. Conductive material ion withhigh energy subsequently directly strikes on the surface of thesubstrate and the hole wall of the hole in very high speed, and implantsbelow the substrate surface and the hole wall for certain depth, forexample 1-500 nm. Steady doping structure is formed between theimplanted conductive material ion and the material constituting thesubstrate, as doping structure in semiconductor. The outer surface ofsuch doping structure (i.e., ion implantation layer) is flush with thesubstrate surface or the hole wall, while inner surface thereofpenetrates inside of the substrate. As a particular example, the ions ofconductive material can gain energy of 50 keV, 100 keV, 200 keV, 300keV, 400 keV, 500 keV, 600 keV, 700 keV, 800 keV, 900 keV during ionimplantation, and can be implanted below the substrate surface and thehole wall for a depth in the range of 10 nm, 20 nm, 50 nm, 100 nm, 200nm, 300 nm, 400 nm.

Various metal, alloy, conductive oxides, conductive carbide, conductiveorganics or the like can be used as conductive material used by ionimplantation, but it is not so limited. Preferably, metal or alloy withstrong binding force with substrate molecule is used to implement ionimplantation, comprising one or more of Ti, Cr, Ni, Cu, Ag, Au, V, Zr,Mo, Nb and alloy thereof, such alloy for example is NiCr, TiCr, VCr,CuCr, MoV, NiCrV, TiNiCrNb or the like. Also, ion implantation layer cancomprise one layer or multi-layer. Before ion implantation,pre-treatment of decontamination, surface cleaning, sealant treatment,Hall source treatment in vacuum environment, surface depositiontreatment or the like can be conducted to substrate with hole.

During ion implantation, the ions of conductive material are forciblyimplanted inside of the substrate in very high speed, form steady dopingstructure with the substrate, this corresponds to forming a large numberof piles below the substrate surface and the hole wall. Because theexisting of piles, and subsequently achieved metal layer (plasmadeposition layer or conductor thickening layer) is connected with thepiles, therefore, the stripping strength between the substrate and themetal layer subsequently formed thereon can reach above 0.5N/mm, forexample between 0.7-1.5N/mm, more specifically between 0.8-1.2N/mm.Compared to that, in conventional magnetron sputtering circumstance, thehighest energy of sputtering particle is only several electronic volts,thus such particle will only deposit on the substrate surface and holewall but will not enter inside of the substrate, binding force betweenthe resultant sputtering deposition layer and substrate surface and holewall is not high, at most only about 0.5N/mm, which is obviously lowerthan the invention. Also, the dimension of the conductive material ionfor ion implantation is usually in nanometer level, are distributedrelatively uniform during ion implantation, and there is no bigdifference for incident angle to the substrate surface and the holewall. Therefore, it can ensure the subsequently formed conductorthickening layer or plasma deposition layer above the ion implantationlayer have good uniformity and compactness, without easily occurring pinhole phenomenon. Also, when micro-hole metalization, it is easy to formsurface uniform compact conductive seed layer on the hole wall, and theratio of the conductor layer thickness of the hole wall and theconductor layer thickness of the substrate surface can reach 1:1,therefore when subsequently electroplating or the like, problems of holewall conductor layer being nonuniform and void or crack or the likedon't occur, which can effectively improve the conductivity of themetalized hole.

In addition to ion implantation, step S3 can also comprise depositing aconductive material above the ion implantation layer via plasmadeposition, to form a plasma deposition layer, such plasma depositionlayer and the ion implantation layer constitute the conductive seedlayer together. As shown in FIG. 2(c), through step S3, ion implantationlayer 131 is formed each below the hole wall 19 of the through hole 17,below the substrate surface 12 in circuit region 161, and below thesurface of the photoresist film 24 in no-circuit region 162, and plasmadeposition layer 132 is formed on such ion implantation layer 131. Ofcourse, step S3 can also not comprise plasma deposition, at the time,the plasma deposition layer 132 shown in FIG. 2(c) doesn't exist, whileonly ion implantation layer 131 exists.

Plasma deposition can be conducted in ion implantation equipmentutilizing similar manner with ion implantation described above, but thatlower voltage is applied to make the conductive material ion have lowerenergy. I.e., using conductive material as target material, in vacuumenvironment, ionizing the conductive material in the target material viaarcing to generate ion, then accelerating such ions in electric field togain certain energy, for example 1-1000 eV. The conductive material ionsafter accelerating fly to the substrate surface and the hole wall anddeposit to the ion implantation layer substrate formed below the surfaceand the hole wall, composing plasma deposition layer in a thickness of1-10000 nm. As a particular example, conductive material ion can gainenergy of 50 eV, 100 eV, 200 eV, 300 eV, 400 eV, 500 eV, 600 eV, 700 eV,800 eV, 900 eV during plasma deposition, and form plasma depositionlayer in a thickness of 100 nm, 200 nm, 500 nm, 700 nm, lμm, 2 μm, 5 μm,7 μm or 10 μm. In the circumstance that the plasma deposition layer isthick, the through hole or blind hole drilled in the substrate might befilled fully. That is to say, all the hole is filled by conductivematerial, macroscopically there is no hole structure existing.

In plasma deposition, conductive materials same or different as ionimplantation can be used as target material. Additionally, conductivematerial can be selected according to the selected substrate, and theconstituting component and thickness of the ion implantation layer orthe like. Preferably, metal or alloy with good binding ability with theion implantation layer can be used to implement plasma deposition, forexample one or more of Ti, Cr, Ni, Cu, Ag, Au, V, Zr, Mo, Nb and alloythereof can be used, such alloy for example is NiCr, TiCr, VCr, CuCr,MoV, NiCrV, TiNiCrNb or the like. Also, plasma deposition layer also cancomprise one layer or multi-layer.

During plasma deposition, the conductive material ions fly to thesubstrate surface and the hole wall in relatively high speed, anddeposited to the ion implantation layer formed on the substrate surfaceand below the hole wall, form relatively large binding force with theconductive material in the ion implantation layer, thus not easily falloff from the substrate surface and the hole wall. Additionally, thedimension of the conductive material ion for ion implantation is usuallyin nanometer level, distributed relatively uniform during ionimplantation, and there is no big difference for incident angle to thesubstrate surface and the hole wall. Therefore, it can ensure theresultant plasma deposition layer or the conductor thickening layersubsequently formed on it have good uniformity and compactness, withouteasily occurring pin hole phenomenon. Additionally, the thickness of theion implantation layer is usually thin, with bad conductivity, while theplasma deposition layer can improve the conductivity of the conductiveseed layer, thereby improving the performance of the resultant circuitboard.

After forming conductive seed layer, the photoresist layer can beremoved, to form circuit pattern on the surface of the substrate (stepS4). As shown in FIG. 2(d), the photoresist film 24 existing inno-circuit region 162 is removed, the conductive seed layer 13 formed onsuch photoresist film 24 is also removed together, while only theconductive seed layer 13 in the circuit region 161 located on the holewall 19 and the substrate surface 12 is left. That is to say, on thesurface of the substrate 12, conductive seed layer 13 only exists in thecircuit region 161, thereby achieving a double-face single-layer circuitboard 10 having circuit pattern. In preferable embodiment, strippingliquid can be used to dissolve photoresist layer, for example, substrateformed with photoresist layer with circuit negative image and conductiveseed layer can be placed into proper stripping liquid, and is stirred orshocked to accelerate the dissolving of the photoresist layer, after thephotoresist layer fully dissolves, using detergent to implement thoroughwashing and subsequently baking. Wherein stripping liquid can be organicsolvent or alkali liquid or the like that can dissolve photoresistlayer.

As shown in FIG. 2(d), single-layer circuit board 10 achieved viaabove-mentioned methods comprises substrate 11 and circuit pattern layer16 formed on partial surface of the substrate, the substrate 11 isprovided with a hole, the conductive seed layer 13 is formed on the holewall of such hole 19, and circuit pattern layer 16 also comprises theconductive seed layer 13 form on partial surface of the substrate 11,the conductive seed layer 13 comprises the ion implantation layer 131implanted below the surface of the substrate 12 and below the hole wallof the hole 19, and the plasma deposition layer 132 adhered on such ionimplantation layer 131. Of course, when step S3 doesn't comprise plasmadeposition, the conductive seed layer 13 is only constituted by ionimplantation layer 131.

Alternatively, after step S3, before step S4, methods shown in FIG. 1can also comprises, form a conductor thickening layer on the conductiveseed layer, to improve the conductivity thereof. In particular, via oneor more of methods of electroplating, chemical plating, vacuumevaporation, sputtering or the like, utilizing one or more of Al, Mn,Fe, Ti, Cr, Co, Ni, Cu, Ag, Au, V, Zr, Mo, Nb and alloy thereof, theconductor thickening layer in a thickness of 0.01-1000 μm (for example0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm or the like) can be formed. Itis easily understood that, in the circumstance of substrate formed withthrough hole or blind hole, such through hole or blind hole might befilled fully by the conductor thickening layer, i.e., macroscopicallythere is no hole structure existing. Electroplating is most common andmost preferable, because for electroplating, the speed is fast, the costis low, and the material range that can be electroplated is very wide,it can used for various conductive material of Cu, Ni, Sn, Ag and alloyof them or the like. For certain conductive material, especially metaland alloy (for example Al, Cu, Ag and alloy thereof), sputtering speedcan reach 100 nm/min, thus sputtering manner can be used to fast coat aconductor layer on the conductive seed layer. Because previously uniformcompact conductive seed layer is already formed via ion implantationand/or plasma deposition on the surface of the substrate and the holewall, so uniform compact conductor thickening layer is easily formed viaabove-mentioned various methods on such conductive seed layer.

In the circumstance of forming with a conductor thickening layer, suchconductor thickening layer will respectively covers the conductive seedlayer, and finally exists on the conductive seed layer in circuit regionafter the photoresist layer is removed, as part of surface circuitpattern of the circuit board. In FIG. 2, the conductive seed layer 13 isconstituted by ion implantation layer 131 and plasma deposition layer132, thus the conductor thickening layer is adhered on the plasmadeposition layer. It is easily understood that, in the circumstance thatthe conductive seed layer only comprises ion implantation layer, theconductor thickening layer is directly adhered on such ion implantationlayer.

According to above-mentioned methods, metalized hole can be formed on asubstrate and circuit pattern can be formed on the surface of suchsubstrate via simple process procedure. When forming circuit pattern,because before forming conductive seed layer, photoresist film isoverlaid in advance on the substrate surface and further forming aphotoresist layer with circuit negative image, afterward using strippingliquid to dissolve such photoresist layer to make the conductive seedlayer and/or conductor thickening layer in non-circuit region fall offtogether with photoresist layer, so there is no need to obtain circuitpattern via etching as prior art, or at least the using of etchingliquid can decrease, thereby decreasing or eliminating the harm to theenvironment by etching waste water containing metal ion.

FIG. 3 represents flowchart of methods for manufacturing single-layercircuit board according to the second embodiment of the invention, whileFIG. 4 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 3. As shown in FIG. 3, such methodscomprises the following steps: drilling a hole on a substrate, the holecomprises blind hole and/or through hole (S1); forming a conductive seedlayer on the surface of substrate and a hole wall of the hole (S2);forming a conductor thickening layer on the conductive seed layer (S31);covering the surface of the substrate with a photoresist film andimplementing exposure, development (S32); and implementing etching,stripping, to form circuit pattern (S33). Wherein step S31 to S33 eachare steps of forming circuit pattern on the surface of the substrate, inthe circumstance of utilizing electroplating to form the conductorthickening layer, these steps can all be known as “panelelectroplating”. FIGS. 4(a), (b), (c), (d) and (e) respectivelycorresponds to above-mentioned step S1, S2, S31, S32 and S33.

In the methods of present embodiment, step S1, S2 respectivelycorresponds to step S1, S3 shown in methods in FIG. 1, it can beconducted utilizing various methods above described for FIG. 1.Additionally, step S31 can also be conducted utilizing methods describedabove, i.e. via electroplating, chemical plating, vacuum evaporation,sputtering or the like, utilizing one or more of Al, Mn, Fe, Ti, Cr, Co,Ni, Cu, Ag, Au, V, Zr, Mo, Nb and alloy thereof, forming the conductorthickening layer with a thickness of 0.01-1000 μm on the conductive seedlayer. Via step S1, S2 and S31, conductive seed layer is each formed onthe surface of substrate and a hole wall of the hole, and conductorthickening layer is formed on such conductive seed layer. In the exampleshown in FIG. 4(c), the conductive seed layer 13 comprises the ionimplantation layer 131 formed below the surface 12 of the substrate 11and below the hole wall of the hole 19, and the plasma deposition layer132 adhered on such ion implantation layer 131, while the conductorthickening layer 15 is further adhered on the plasma deposition layer132, and such conductor thickening layer 15 fills fully throughout thethrough hole 17 of the substrate 11. It is easily understood that, inthe circumstance that step S2 only comprises ion implantation butdoesn't comprise plasma deposition, the conductor thickening layer 15 isdirectly adhered on the ion implantation layer 131.

After forming conductor thickening layer, covering the surface of thesubstrate with a photoresist film and implementing exposure, development(step S32). In particular, as shown in FIG. 4(d), painting or stickingone layer photoresist film 24 on the substrate surface 12 formed withconductor thickening layer 15, placing the substrate overlaid withphotoresist film 24 on a lithography machine to implement exposure anddevelopment, after washing the substrate surface and baking, obtaining aphotoresist layer having circuit positive image (i.e. forming the sameimage of the circuit pattern to be finally formed on the substratesurface). At the time, photoresist film 24 only exists in circuit region161 on the substrate surface, and the complementary no-circuit region162 thereof doesn't comprise such photoresist film 24.

Then, conventional etching methods can be utilized to remove theconductive seed layer and the conductor thickening layer not covered byphotoresist film, subsequently stripping photoresist film (step S33),thereby the conductive seed layer and the conductor thickening layer isonly left in the circuit region on the substrate surface, formingsurface circuit pattern. As shown in FIG. 4(e), the single-layer circuitboard 10 achieved via above-mentioned methods comprises substrate 11 andpattern layer 16 formed on partial surface of the substrate circuit, thesubstrate 11 is provided with a hole, a conductive seed layer 13 andconductor thickening layer 15 are formed on the hole wall of such hole19, and circuit pattern layer 16 also comprises conductive seed layer 13and conductor thickening layer 15, wherein the conductive seed layer 13comprises the ion implantation layer 131 implanted below the surface ofthe substrate 12 and below a hole wall of the hole 19, and the plasmadeposition layer 132 adhered on such ion implantation layer 131. Ofcourse, in the circumstance that step S2 doesn't comprise plasmadeposition; the conductive seed layer 13 is only constituted by ionimplantation layer 131.

FIG. 5 represents flowchart of methods for manufacturing single-layercircuit board according to the third embodiment of the invention, whileFIG. 6 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 5. As shown in FIG. 5, such methodscomprise the following steps: drilling a hole on a substrate, the holecomprises blind hole and/or through hole (S1); forming a conductive seedlayer on the surface of substrate and a hole wall of the hole (S2);covering the surface of the substrate with a photoresist film andimplementing exposure, development (S31); implementing electroplating(S32); and implementing stripping, etching, to form circuit pattern(S33). Wherein step S31 to S33 each are steps to form circuit pattern onthe surface of the substrate, generally known as “patternelectroplating”. Compared to the methods shown in FIG. 3, the differenceof the methods of present embodiment is that, pattern electroplating isutilized rather than panel electroplating to form circuit pattern. FIG.6 (a), (b), (c), (d) and (e) respectively corresponds to above-mentionedstep S1, S2, S31, S32 and S33.

In the methods of present embodiment, step S1, S2 respectivelycorresponds to step S1, S2 in the methods shown in FIG. 3, it can beconducted utilizing various methods above described for FIG. 3. Afterstep S2, the surface of the substrate and the hole wall of the hole eachare formed with conductive seed layer. As shown in FIG. 6(b), theconductive seed layer 13 comprises the ion implantation layer 131 formedbelow the surface 12 of the substrate 11 and below the hole wall of thehole 19, and the plasma deposition layer 132 adhered on such ionimplantation layer 131. It is easily understood that, in thecircumstance that step S2 only comprises ion implantation but doesn'tcomprise plasma deposition, the plasma deposition layer 132 doesn'texist. Additionally, step S31 can also conducted utilizing similarmanner with step S32 in the methods shown in FIG. 3, i.e., covering thesubstrate surface formed with conductive seed layer with a photoresistfilm and implementing exposure, development. In particular, as shown inFIG. 6(c), painting or sticking one layer photoresist film 24 on thesubstrate surface 12 formed with conductive seed layer 13, placing thesubstrate overlaid with photoresist film 24 on a lithography machine toimplement exposure and development, after washing substrate surface andbaking, obtaining photoresist layer having circuit negative image. Atthe time, the photoresist film 24 only exists in the no-circuit region162 on the substrate surface, and the complementing circuit region 161thereof doesn't comprise photoresist film 24.

Subsequently, there is need to implement electroplating (step S32).Because the photoresist layer is insulated, thus in electroplatingprocess, the conductor thickening layer doesn't form above thephotoresist layer, but rather only form above the conductive seed layernot covered by photoresist layer. At the time, below the photoresistlayer, there exists conductive seed layer constituted by the ionimplantation layer and the plasma deposition layer, but above thephotoresist layer, there doesn't comprise conductor thickening layer. Asshown in FIG. 6(d), via electroplating, conductor thickening layer 15 isonly formed on the conductive seed layer 13, and such conductorthickening layer 15 fills fully through hole 17. Of course, in thecircumstance that the diameter of the through hole 17 is big enough,such through hole 17 will not be filled fully by the conductorthickening layer 15.

Then, there is need to implement stripping, etching, to form circuitpattern (step S33), thereby achieving single-layer circuit board. Thesingle-layer circuit board 10 shown in FIG. 6(e) has the sameconfiguration with the single-layer circuit board 10 shown in FIG. 4(e).

Stripping is stripping photoresist layer having circuit negative image,it can be conducted via steps as following: placing the insulatedsubstrate formed with the conductive seed layer, the photoresist layerand the conductor thickening layer in a proper stripping liquid (forexample, organic solvent or alkali liquid or the like that can dissolvethe photoresist layer), and is stirred or shocked to accelerate thedissolving of the photoresist layer, afterward implementing washing andbaking. Thereby, there are conductive seed layer and conductorthickening layer in the circuit region on the substrate surface, whilethere is only conductive seed layer in the no-circuit region. Then, fastetching can be conducted to all the surface of the metal base plate, toremove the conductive seed layer in the no-circuit region, obtainingfinal circuit pattern on the substrate surface. At the time, theconductor thickening layer in the circuit region will also be etchedcertain thickness corresponding to the conductive seed layer, but itdoesn't affect its subsequent usage. Alternatively, it also can be that,after the photoresist layer fully dissolves, overlaying one layerprotection layer (for example tin) above the conductor thickening layerlocated in the circuit region, afterward implementing etching to removethe conductive seed layer located in the no-circuit region, therebyobtaining final circuit pattern. At the time, the conductor thickeninglayer in the circuit region will not be etched, thereby maintaining goodsurface property of the conductor thickening layer. Additionally, italso can be that, before placing the substrate in the stripping liquid(i.e., before the photoresist layer dissolves), overlaying one layerprotection layer (for example tin) above the conductor thickening layerlocated in the circuit region, subsequently successively implementingdissolving of the photoresist layer and etching removing of theconductive seed layer in the no-circuit region, obtaining final circuitpattern on the substrate surface. Of course, in the circumstance thatprotection layer is utilized, it also need to remove such protectionlayer before gaining final circuit pattern, for example it need to takethe step of stripping tin film.

According to methods for manufacturing single-layer circuit boarddescribed above, metalization of the substrate surface and metalizationof the hole can be conducted simultaneously. Therefore, single-layercircuit board with metalized via hole can be directly achieved on thesubstrate via one time forming, without needing as prior art that, itneed to overlay thick metal foil to the substrate in advance andafterward implement etching thinning to metal foil to drill a hole onthe substrate, and it need to further form conductive layer on the holewall via process of chemical electroless copper or black hole, shadow orthe like, to obtain metalized via hole. Compared to prior art, theprocess procedure of the methods above is significantly shorter, and candecrease the using of etching liquid, facilitating protection of theenvironment. Additionally, via adjusting various process parameter,these methods very easily achieve very thin circuit pattern layer inthickness (for example, below 12 μm, such as 5 μm, 7 μm, 9 μm or thelike), the resultant single-layer circuit board can advantageously beapplied to medium and high grade precision electronic product on thebasis of HDI (high density interconnected base plate) and COF (flexiblechip) technology.

Also, because of the existing of ion implantation layer in the holewall, the single-layer circuit board achieved via several methodsmentioned above can have very high binding force between the hole walland the conductive seed layer (for example above 0.5N/mm, such asbetween 0.7-1.5N/mm, more specifically between 0.8-1.2N/mm), thus theconductive layer of the hole wall wouldn't easily fall off or scuff inthe subsequent various fabrication or application process. Therefore, itfacilitates improving the conductivity of the hole, facilitatingachieving single-layer circuit board with good connectivity.

It should be noted that, although in the methods shown in FIG. 3 panelelectroplating is utilized to form circuit pattern (i.e., successivelyforming conductor thickening layer, covering with photoresist film andimplementing exposure and development, implementing etching stripping),while in the methods shown in FIG. 5 pattern electroplating is utilizedto form circuit pattern (i.e., successively covering with photoresistfilm and implementing exposure and development, implementingelectroplating, implementing stripping etching), but it is easilyunderstood that, it can also be that, first forming a conductorthickening layer on the conductive seed layer, then implementing panelelectroplating based on that, or it can also be that, implementingpattern electroplating directly on the conductive seed layer (forexample in the circumstance that the conductive seed layer is thick).

Several methods of manufacturing single-layer circuit board is describedabove, in the following, several method embodiment of manufacturingmulti-layer circuit board will be described according to the invention.

FIG. 7 represents flowchart of methods for manufacturing multi-layercircuit board according to the fourth embodiment of the invention, whileFIG. 8 represents sectional schematic view of respective product of eachstep of the methods shown in FIG. 7. As shown in FIG. 7, such methodscomprise the following steps: implementing laying-up plate andlamination in the order of metal foil, middle sticking layer,single-layer circuit board, middle sticking layer, single-layer circuitboard, . . . , middle sticking layer, metal foil (step S1); drilling ahole on the multi-layer plate after lamination, the hole comprises blindhole and/or through hole (S2); forming a conductive seed layer on thehole wall of the hole (S3); and removing part of the metal foil, to formcircuit pattern (S4). FIGS. 8 (a), (b), (c) and (d) respectivelycorresponds to step S1, S2, S3 and S4. In the following, reference ismade to FIG. 7 and FIG. 8 simultaneously, illustrating each step of suchmethods in detail.

In step S1, the layer number of single-layer circuit board can beadjusted according the need, for example it can be one layer ormulti-layer. When the layer number of single-layer circuit board is onelayer, it can finally obtain three-layers circuit board, while when thelayer number of single-layer circuit board is two layers, it can finallyobtain four-layers circuit board. Also, each single-layer circuit boardcan be the same or different circuit board. As an example of metal foil,a material with good conductivity of copper foil or aluminum foil or thelike is usually used. Additionally, middle sticking layer is used tostitch together between single-layer circuit board, and betweensingle-layer circuit board and metal foil, it can usually use PP, PI,PTO, PC, PSU, PES, PPS, PS, PE, PEI, PTFE, PEEK, PA, PET, PEN, LCP, PPAor the like, or pure resin adhesive film without containing glass fabric(for example epoxy resin adhesive film). Additionally, each stickinglayer between each single-layer circuit board, and between single-layercircuit board and metal foil can be made by the same material, also canbe made by different material. In the example shown in FIG. 8(a), twolayer of single-layer circuit board 10 prepared via methods shown inFIG. 1 is utilized, such single-layer circuit board 10 is provided witha hole and formed with ion implantation layer 131 implanted below thehole wall and below partial surface and plasma deposition layer 132adhered above such ion implantation layer. Of course, single-layercircuit board used here can also be single-layer circuit board onlyhaving ion implantation layer 131 as shown in FIG. 2, with a hole havingconductive layer or without a hole, and it can also be circuit boardachieved utilizing metal foil which is common in the art. Also, themiddle sticking layer used here also can be sticking layer having a holeespecially through hole, wherein the hole wall of the hole is formedwith conductive layer. Such conductive layer can be the conductive seedlayer comprising ion implantation layer as described herein, it can alsobe metal layer formed via methods of conventional magnetron sputteringor the like, as long as it can be conductive.

Subsequently, drilling a hole on the multi-layer plate after lamination(step S2), such hole can comprise blind hole and/or through hole. StepS2 corresponds to step S1 in the methods shown in FIG. 1, it can utilizethe same manner thereof. As shown in FIG. 8(b), through hole 17 andblind hole 18 is formed in the multi-layer plate after lamination, thethrough hole 17 runs through all the multi-layer plate, while the blindhole 18 only runs through metal foil 21 and middle sticking layer 22adjacent such metal foil. Of course, it can only form through hole 17 orblind hole 18.

Then, forming conductive seed layer on the hole wall of the hole (S3).Such step S3 is similar to step S3 in the methods shown in FIG. 1; itcan utilize the same manner thereof. The difference is that, becausemetal foil is located on the outer surface of multi-layer plate, themethods of the embodiment don't have to form conductive seed layer onthe surface of the metal foil, but rather it only need to form theconductive seed layer on the hole wall. Of course, in the circumstanceof implementing ion implantation or plasma deposition without takingprotection measures to the metal foil, conductive seed layer will alsoformed on the outer surface of the metal foil. As shown in FIG. 8(c),the hole wall 19 of the through hole 17 and the blind hole 18, each areformed with a conductive seed layer constituted by ion implantationlayer 131 implanted below the hole wall 19 and the plasma depositionlayer 132 adhered above such ion implantation layer 131. Of course, whenstep S3 doesn't comprise plasma deposition, the conductive seed layer isonly constituted by ion implantation layer 131 implanted below the holewall 19.

Finally, removing part of the metal foil, to form circuit pattern (stepS4). Because the metal foil has conductivity, thus in such step, it onlyneed to use common manner of etching or the like, to remove the metalfoil in the no-circuit region, then if can gain multi-layer circuitboard having surface circuit pattern. For example, in step S4, one layerof protection layer (for example tin) can be overlaid above the surfaceof the metal foil to be formed of circuit region, afterward implementingetching to remove the metal foil in the no-circuit region, therebyobtaining final circuit pattern.

As shown in FIG. 8(d), the metal foil 21 in the no-circuit region 162 isremoved, only the metal foil 21 in the circuit region 161 is left,thereby forming circuit pattern 16. The multi-layer circuit board 20achieved via above-mentioned methods is successively constituted bymetal foil 21, middle sticking layer 22, single-layer circuit board 10,middle sticking layer 22, single-layer circuit board 10, middle stickinglayer 22, metal foil 21, such multi-layer circuit board 20 is providedwith hole 17, 18, a conductive seed layer is formed on the hole wall ofthe hole 19, and partial region of the metal foil 21 is removed to formcircuit pattern layer 16, wherein the conductive seed layer comprisesthe ion implantation layer 131 implanted below the hole wall 19 and theplasma deposition layer 132 adhered on such ion implantation layer 131.Of course, the conductive seed layer can also be constituted by the ionimplantation layer 131. Also, multi-layer circuit board 20 furthercomprises through hole throughout such multi-layer circuit board, blindhole formed on the surface thereof, and blind hole formed in thesingle-layer circuit board and the middle sticking layer.

Alternatively, after step S3, before step S4, the methods of theembodiment can also comprise, forming a conductor thickening layer onthe conductive seed layer, to improve its conductivity. The forming ofconductor thickening layer be conducted via methods described above.

According to the methods shown in FIG. 8, a hole is formed inmulti-layer circuit board, and an ion implantation layer is formed belowthe hole wall of such hole via ion implantation. As discussed above, ionimplantation aids to form relatively large binding force between thesubstrate and the conductive seed layer, and can make the surface of theconductive seed layer have good uniformity and compactness, withouteasily occurring of pin hole phenomenon. Additionally, when micro-holeis metalized, problems of hole wall conductor layer being nonuniform andvoid or crack or the like will not occur, it thus can effectivelyimprove the conductivity of the metalized hole.

FIG. 9 represents flowchart of methods for manufacturing multi-layercircuit board according to the fifth embodiment of the invention, whileFIGS. 10A and 10B represent sectional schematic views of respectiveproducts of each step of the methods shown in FIG. 9. As shown in FIG.9, such methods comprise the following steps: implementing laying-upplate and lamination in the order of surface sticking layer,single-layer circuit board, middle sticking layer, single-layer circuitboard, . . . , surface sticking layer (step S1); drilling a hole on themulti-layer plate after lamination, the hole comprises blind hole and/orthrough hole (S2); forming a conductive seed layer on the outer surfaceof the surface sticking layer and the hole wall of the hole (S3);forming a conductor thickening layer on the conductive seed layer (S41);covering the outer surface of the surface sticking layer with aphotoresist film and implementing exposure, development (S42); andimplementing etching, stripping, to form circuit pattern (S43). Whereinstep S41 to S43 each are steps to form circuit pattern on the outersurface of the surface sticking layer, in the circumstance of formingconductor thickening layer utilizing electroplating, these steps can begenerally known as “panel electroplating”. FIGS. 10A (a), (b), (c), and10B (d), (e) and (f) respectively corresponds to above-mentioned stepS1, S2, S3, S41, S42 and S43.

In the methods of present embodiment, step S1 is similar to step S1 inthe methods shown in FIG. 7, the difference is that metal foil is notutilized; step S2 corresponds to step S2 in the methods shown in FIG. 7;step S3 is similar to step S3 in the methods shown in FIG. 7, thedifference is that, the conductive seed layer is formed not only on thehole wall of the hole, but also on the outer surface of the surfacesticking layer. Additionally, step S41 to S43 respectively correspondsto step S31 to S33 n the methods shown in FIG. 3, it can utilize similarpanel electroplating manner thereof.

As shown in FIG. 10B(f), via multi-layer circuit board 20 achieved bythe methods of the embodiment is constituted successively by surfacesticking layer 23, single-layer circuit board 10, middle sticking layer22, single-layer circuit board 10, surface sticking layer 23, suchmulti-layer circuit board 20 is provided with hole 17, 18, a conductiveseed layer is formed on the hole wall of the hole 19, and a circuitpattern layer having a conductive seed layer 16 is formed on partialouter surface of the surface sticking layer 23, wherein the conductiveseed layer comprises ion the implantation layer 131 implanted below thehole wall 19 and below partial outer surface of the surface stickinglayer 23 and the plasma deposition layer 132 adhered on such ionimplantation layer 131. Of course, the conductive seed layer can also beconstituted by the ion implantation layer 131. Circuit pattern layer 16further comprises conductor thickening layer 15, of course this is notnecessary.

FIG. 11 represents flowchart of methods for manufacturing multi-layercircuit board according to the sixth embodiment of the invention, whileFIGS. 12A and 12B represent sectional schematic views of respectiveproducts of each step of the methods shown in FIG. 11. Such methodscomprises the following steps: implementing laying-up plate andlamination in the order of surface sticking layer, single-layer circuitboard, middle sticking layer, single-layer circuit board, . . . ,surface sticking layer (step S1); drilling a hole on the multi-layerplate after lamination, the hole comprises blind hole and/or throughhole (S2); forming a conductive seed layer on the outer surface of thesurface sticking layer and the hole wall of the hole (S3); covering theouter surface of the surface sticking layer with a photoresist film andimplementing exposure, development (S41); implementing electroplating(S42); and implementing stripping, etching, to form circuit pattern(S43). Wherein step S41 to S43 each are steps to form circuit pattern onthe outer surface of the surface sticking layer, generally known as“pattern electroplating”. Compared to the methods shown in FIG. 9, thedifference of the methods of this embodiment is that, patternelectroplating is utilized rather than panel electroplating to formcircuit pattern. FIGS. 12A (a), (b), (c), and 12B (d), (e) and (f)respectively corresponds to above-mentioned step S1, S2, S3, S41, S42and S43.

In the methods of present embodiment, step S1, S2 and S3 respectivelycorresponds to step S1, S2 and S3 in the methods shown in FIG. 9, it canbe conducted utilizing various methods above described for FIG. 9.Additionally, step S41 to S43 respectively correspond to step S31 to S33in the methods shown in FIG. 5, it can utilize similar panelelectroplating manner thereof. As shown in FIG. 12B(f), the multi-layercircuit board 20 achieved via the methods of this embodiment has thesame configuration with the multi-layer circuit board 20 shown in FIG.10B(f).

According to the methods of manufacturing multi-layer circuit boardshown in FIG. 9 or FIG. 11, the metalization of the outer surface of thesurface sticking layer and metalization of the hole can be conductedsimultaneously. Therefore, multi-layer circuit board having metalizedvia hole and surface circuit pattern can be directly achieved on thesubstrate via one time forming, without needing as prior art that, itneed to overlay thick metal foil in advance and afterward implementetching thinning to metal foil to drill a hole on the substrate, and itneed to further form conductive layer on the hole wall via process ofchemical electroless copper or black hole, shadow or the like, to obtainmetalized via hole. Compared to prior art, the process procedure of themethods above is significantly shorter, and can decrease the using ofetching liquid, facilitating protection of the environment.Additionally, via adjusting various process parameter, these methodsvery easily achieve very thin circuit pattern layer in thickness (forexample, below 12 μm, such as 5 μm, 7 μm, 9 μm or the like), theresultant multi-layer circuit board can advantageously be applied tomedium and high grade precision electronic product on the basis of HDI(high density interconnected base plate) and COF (flexible chip)technology.

Also, because of the existing of ion implantation layer in the holewall, the multi-layer circuit board achieved via several methodsmentioned above can have very high binding force between the hole walland the conductive seed layer, thus the conductive layer of the holewall wouldn't easily fall off or scuff in the subsequent variousfabrication or application process. Therefore, it facilitates improvingthe conductivity of the hole, facilitating achieving multi-layer circuitboard with good connectivity.

The text above in detail describes methods of manufacturing single-layercircuit board, multi-layer circuit board, and particular configurationof single-layer and multi-layer circuit board achieved via these methodsaccording to the invention. In the following, several examples ofimplementing the invention will be illustrated by example, to increasethe understanding of the invention.

Example 1

Such example uses organic polymer thin film as substrate to makeflexible circuit board having metalized hole, particularly utilizingliquid crystal polymer thin film (LCP film) as substrate.

First, the surface of LCP film is rubbed using gauze impregnated byalcohol, to remove the dirt adhered above. Subsequently, a series ofthrough holes with the diameter of 20 μm are drilled on such LCP filmutilizing laser drilling technology, then the surface of LCP film andthe hole wall are thoroughly cleaned using blower or the like, to removedrilling scrap and other dirt left therein.

Then, one layer of photoresist film is painted on the cleaned LCP filmsubstrate surface, and such substrate is placed on a lithography machineto implement exposure and development, afterward material in the regionis washed away to form circuit pattern on the substrate surface (alsoknown as circuit region), circuit negative image overlaid withphotoresist film coating (also known as photoresist layer) is obtained.At the time, photoresist layer only exists in the no-circuit region onthe substrate surface.

Subsequently, the substrate formed with photoresist layer having circuitnegative image after exposure and development is placed into an oven tobake, subsequently it is transferred into an ion implantation equipmentto implement ion implantation. In such ion implantation equipment, theion implantation chamber is vacuumed to 8.5×10⁻³ Pa, Ni is used astarget material, proper implanting voltage, implanting current selected,such that the ionized Ni ion has an implanting energy of about 60 keV,and ion implantation is implemented to the surface of LCP film substrateand the hole wall, Ni ion is implanted below the surface of LCP filmsubstrate and below the hole wall. Afterward, Cu is used as targetmaterial, plasma deposition is implemented on the surface of LCP filmand the hole wall. At the time, the voltage of plasma deposition can beadjusted to make the energy of deposited Cu ion is 1000 eV, such thatthe measured sheet resistivity of overlaying copper plate substrateafter plasma deposition is less than 30Ω/□.

Then, the copper film on LCP film substrate surface is thickened to 5 μmvia magnetron sputtering methods. The particular process is: in thecoating chamber of the magnetron sputtering machine, vacuuming to 10⁻²Pa, filling argon, adjusting the pressure therein to 10 Pa, implementingcleaning of the thin film surface, afterward vacuuming to be 10⁻³ Pa,adjusting working voltage to be 500V, sputtering duty ratio to be 70%,using copper as target material, implementing sputtering to the surfaceof LCP film substrate and the hole wall, overlaying one layer of copperlayer in a thickness of 5 μm above them.

Afterward, LCP film substrate formed with photoresist layer havingcircuit negative image, conductive seed layer and conductor thickeninglayer is placed into respective stripping liquid that can dissolve suchphotoresist layer, and is stirred or shocked to accelerate thedissolving of the photoresist layer. In the dissolving process of thephotoresist layer, the conductive seed layer above such photoresistlayer and the conductor thickening layer also peels off from thesubstrate surface into the stripping liquid therewith. After thephotoresist layer with circuit negative image fully dissolves, properdetergent can be used to implement thorough washing to the surface ofthe substrate, afterward it is placed in the oven to bake, and desiredcircuit pattern can be obtained in this way on the surface of thesubstrate.

Finally, annealing treatment can be conducted to the achieved circuitboard, i.e., placing the circuit board in the oven of 80-100° C. forbaking 15 hours, to eliminate stress existing in the copper layer andpreventing the copper layer rupture. Subsequently, the circuit board canbe also placed into passivation liquid to soak for about 1 minute thenit is took out for blow drying, to prevent copper from oxidation stainin the air, wherein passivation liquid is the water solution ofbenzotriazole and ramification thereof in a concentration of 1 g/L.

Example 2

Such example uses epoxy glass fabric as substrate to manufacture rigidsingle-layer circuit board having metalized hole, in turn uses suchsingle-layer circuit board to make multi-layer circuit board,particularly using FR-4 or FR-5 substrate of the epoxy glass fabricsubstrate.

First, the surface of FR-4 substrate is rubbed using gauze impregnatedby alcohol; to remove the dirt adhered above. Subsequently, severalthrough holes with the diameter of about 100 μm and several blind holeswith the diameter of about 100 μm and in a depth of about 200 μm aredrilled on such FR-4 substrate utilizing laser drilling technology.After drilling the holes, the surface of FR-4 substrate and the holewall are further thoroughly washed using ultrasonic technology andbaking treatment is implemented, to remove drilling scrap and other dirtleft therein.

Subsequently, the substrate after baking is placed into an ionimplantation equipment via feeding mechanism, the ion implantationchamber is vacuumed to 2×10⁻³ Pa, Ni used as target material, properimplanting voltage, implanting current is selected, such that theimplanting energy of Ni ion is 30 keV, and Ni ion is implanted below thesurface of FR-4 substrate and below the hole wall. Afterward, Cu is usedas target material, plasma deposition is implemented on the the surfaceof FR-4 substrate and the hole wall. The voltage of plasma depositioncan be adjusted to make the energy of deposited Cu ion to be 1000 eV,such that the measured sheet resistivity of FR-4 substrate formed withconductive seed layer is less than 50Ω/□.

Subsequently, one layer of photoresist film is sticked on the surface ofFR-4 substrate formed with conductive seed layer, and such substrate isplaced on a lithography machine to implement exposure and development,afterward material in the circuit region on the substrate surface iswashed away, obtaining photoresist layer having circuit negative image.At the time, photoresist layer only exists in the no-circuit region onthe substrate surface, but conductive seed layer also exists below suchphotoresist layer.

Then, the copper film in the circuit region on the substrate surface isthickened to 5 μm on electroplating copper producing line. Theconstituting components of electroplating liquid are copper sulfate 100g/L, sulfuric acid 50 g/L, chlorine ion concentration 30 mg/L and asmall amount of additive; the current density of electroplating is setto be 1 A/dm²; temperature is set to be 10° C. In the electroplatingprocess, photoresist layer can't be coated by copper layer because ofthe insulated property thereof. That is to say, electroplated conductorthickening layer will only exist in the region on the substrate surfacewhere photoresist layer doesn't exist, i.e., circuit region.

Afterward, FR-4 substrate formed with conductive seed layer, photoresistlayer having circuit negative image, and conductor thickening layerplaced into respective stripping liquid that can dissolve suchphotoresist layer, and is stirred to accelerate the dissolving of thephotoresist layer. After the photoresist layer fully dissolves, theconductive seed layer below it will be exposed. Subsequently, one layerof tin on the conductor thickening layer of the substrate surfaceoverlaid as protection layer, afterward etching is implemented to thesubstrate, to remove the conductive seed layer outside of the region ofconductor thickening layer (i.e. circuit region). Finally, the platedtin layer on the conductor thickened layer is torn off and desiredcircuit pattern is obtained. Alternatively, it also can be that, firstone layer of tin is overlaid on the conductor thickening layer of thesubstrate surface as protection layer, then photoresist layer is removedusing stripping liquid, subsequently the conductive seed layeroriginally located below the photoresist layer is removed via etching.As such, single-layer circuit board with metalized hole and surfacecircuit pattern is obtained.

Subsequently, epoxy resin adhesive film used as sticking layer,laying-up plate is implemented successively in the order of copper foil,epoxy resin adhesive film, single-layer circuit board, epoxy resinadhesive film, single-layer circuit board, epoxy resin adhesive film,copper foil from down to up, and it is placed into a press machine forlamination, to form multi-layer plate. Of course, according to the need,more or less layer number of single-layer circuit board can be alsoutilized.

Then, mechanical drilling bit is used to drill several through holeswith the diameter of about 100 μm on the resultant multi-layer plate,and drill several blind holes with the diameter of about 100 μm on theupper layer of copper foil and epoxy resin adhesive film. After drillingthe holes, the surface of multi-layer plate and the wall surface of thehole are further thoroughly cleaned using ultrasonic technology andbaking treatment is implemented, to remove drilling scrap and other dirtleft therein.

Then, hole metalization is implemented to the formed through hole andblind hole. In particular, the multi-layer plate after baking andcleaning is placed into the ion implantation equipment via feedingmechanism, the ion implantation chamber is vacuumed to 2×10⁻³ Pa. Ni isused as target material, proper implanting voltage, implanting currentis selected, such that the implanting energy of Ni ion is 30 keV, and Niion is implanted within the upper and lower surface and the hole wall ofthe multi-layer plate, forming ion implantation layer. Afterward, Cu isselected as target material, plasma deposition is implemented on theupper and lower surface and the hole wall of the multi-layer plate,forming plasma deposition layer. The voltage of plasma deposition can beadjusted to make the energy of deposited Cu ion to be 1000 eV, such thatthe measured sheet resistivity of the FR-4 substrate formed withconductive seed layer is less than 50Ω/□. Then, the copper film on theconductive seed layer is thickened to 5 μm on the electroplating copperproducing line. The constituting components of electroplating liquid arecopper sulfate 100 g/L, sulfuric acid 50 g/L, chlorine ion concentration30 mg/L and a small amount of additive; the electroplated currentdensity is set to be 1 A/dm²; temperature is set to be 10° C.

Subsequently, on the upper layer copper foil of the multi-layer plateformed with metalized hole, desired circuit pattern is gained viapattern electroplating methods. That is to say, the surface of thecopper foil (for example YQ-30SD film or AQ-2058 film which is negative)is covered with photoresist film upper layer, exposure and developmentare implemented, afterward the material in the no-circuit region iswashed away. At the time, photoresist layer only exists in the circuitregion on the copper foil surface, while the copper foil in theno-circuit region is exposed. Subsequently, etching is implementedutilizing acidic etching liquid (HCl+CuCl₂), to remove the copper foilin the no-circuit region. Then, NaOH solution utilized to implementstripping, stripping the photoresist film still covering on the copperfoil, so as to expose the copper foil below, and finally obtainingdesired surface circuit pattern.

Optionally, annealing treatment can also be conducted to the achievedmulti-layer circuit board, to eliminate the stress existing therein,preventing copper foil rupture, the particular process can be: placingthe multi-layer circuit board in the oven of 100-120° C. for baking 12hours. Subsequently, the circuit board after annealing treatment can bealso placed into passivation liquid to soak for about 1 minute then itis took out for blow drying, to prevent copper from oxidation stain inthe air, wherein passivation liquid is the water solution ofbenzotriazole and ramification thereof in a concentration of 2 g/L.

Example 3

This example uses double-face flexible overlaying copper plate withorganic polymer thin film (for example, PI film) as substrate to makesingle-layer circuit board, further uses such single-layer circuit boardto make multi-layer circuit board.

First, single-layer circuit board is prepared. In particular, PI film isused as substrate, two surfaces of PI film are rubbed using gauzeimpregnated by alcohol, to remove the dirt adhered above. Subsequently,a series of through holes with the diameter of 10 μm on PI film aredrilled utilizing ultraviolet laser drilling technology, and the surfaceand the hole wall of PI film are thoroughly washed using ultrasonictechnology, to remove drilling scrap and other dirt left therein.Subsequently, PI film after drilling is placed into ion implantationequipment. In such ion implantation equipment, the ion implantationchamber is vacuumed to 1×10⁻⁴ Pa, Ni is used as target material, properimplanting voltage, implanting current is selected, such that the energyof implanting Ni ion is 40 keV, Ni ion is implanted within both theupper and lower surface and the hole wall of the PI film substrate.Afterward, Cu is selected as target material, plasma deposition isimplemented on both the upper and lower surface and the hole wall of themulti-layer plate. The voltage of plasma deposition is adjusted to makethe energy of deposited Cu ion to be 500 eV, such that the measuredsheet resistivity of the PI film substrate formed with conductive seedlayer is less than 40Ω/□.

Subsequently, the copper film PI film on the substrate surface isthickened to 5 μm on electroplating copper producing line. In suchelectroplating process, the constituting components of theelectroplating liquid are copper sulfate 160 g/L, sulfuric acid 70 g/L,chlorine ion concentration 60 mg/L and a small amount of additive;electroplated current density is set to be 2.5 A/dm²; temperature is setto be 25° C. Then, one layer of photoresist film is painted on thethickened copper layer of the PI film substrate, and it is placed in alithography machine to conduct exposure and development, afterward thematerial in the no-circuit region on the substrate surface is washedaway, obtaining circuit positive image overlaid by photoresist film. Atthe time, photoresist layer only exists in the circuit region on theconductive seed layer surface.

Afterward, etching is implemented to etch away the conductive seed layerin the no-circuit region; the circuit region is not etched because ofthe protection function of the photoresist film. Stripping liquid isused again to remove photoresist film, afterward the substrate afterstripping is placed into the oven for baking, and desired circuitpattern is obtained on the surface of the substrate in this way.Thereby, single-layer circuit board with circuit pattern and metalizedhole is gained; such single-layer circuit board can be subsequently usedfor manufacturing multi-layer circuit board.

Then, PP film is used as sticking layer, laying-up plate is implementedsuccessively in the order of PP, single-layer circuit board, PP,single-layer circuit board, PP from down to up, and it is placed in apress machine for lamination, to form multi-layer plate. Subsequently,laser drilling technology is utilized, several through holes with thediameter of 10 μm are drilled on the resultant multi-layer plate, andseveral blind hole with the diameter of 10 μm is drilled on upper layerof PP. After drilling, the surface of the multi-layer plate and the holewall of the hole is thoroughly cleaned utilizing technology ofultrasonic washing or the like, and drying treatment is implemented, toremove drilling scrap and other dirt or the like left therein.

Subsequently, the multi-layer plate after drilling is placedsuccessively into ion implantation equipment and plasma depositionequipment, conductive seed layer on the surface of upper layer PP filmand the hole wall of the hole is formed as described above. To formcircuit, subsequently both the upper and lower surface of the upperlayer PP film formed with thickening copper film (for example YQ-40PNfilm or ASG-302 film which is positive) are covered with a photoresistlayer, and it is placed into a lithography machine to implement exposureand development, afterward unwanted photoresist film material in thecircuit region is washed away, only the conductive seed layer in thecircuit region is exposed. Then, the copper film of conductive seedlayer in the circuit region of PP film surface and the hole wall isthickened to 5 μm via electroplating. After electroplating, then onelayer of tin in a thickness of 8 μm is electroplated on its surface, toprotect such plated copper layer in subsequent etching process.Subsequently, NaOH (or KaOH) solution is used to implement stripping, soas to expose the conductive seed layer outside of the circuit region.Then, alkalic etching liquid NH₄Cl/NH₃.H₂O is used to etch theconductive seed layer outside the circuit region, and HNO₃ or H₂O₂solution or the like is used to remove the tin on the plated copperlayer surface in dedicated equipment, in this way multi-layer circuitboard having circuit pattern is obtained. At the time, the multi-layercircuit board has the sectional structure as shown in FIG. 10B(f).

The above described content only mentions optimum embodiment of thepresent invention. However, the present invention is not limited to theparticular embodiment described herein. It easily occurs to thoseskilled in the art that, without departing the range of subjectivematter of the present invention, various obvious modification,adjustment and replacement can be made to these embodiments, to adapt itto particular situation. Actually, the patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

What is claimed is:
 1. A single-layer circuit board, comprisingsubstrate and circuit pattern layer formed on partial surface of saidsubstrate, said substrate is provided with a hole, the hole comprisesblind hole and/or through hole, the hole wall of said hole is formedwith conductive seed layer, said circuit pattern layer comprisesconductive seed layer formed to partial surface of said substrate,wherein said conductive seed layer comprises ion implantation layerimplanted below partial surface of said substrate and below the holewall of said hole.
 2. The single-layer circuit board of claim 1, whereinsaid ion implantation layer is located below partial surface of saidsubstrate and below the hole wall of said hole for a depth of 1-500 nm,and forms steady doping structure with said substrate.
 3. Thesingle-layer circuit board of claim 1, wherein said conductive seedlayer further comprises plasma deposition layer adhered above said ionimplantation layer, said plasma deposition layer has a thickness of1-10000 nm.